The present invention relates to a bobbin holder, especially, a bobbin holder installed in a yarn winding apparatus for winding a synthetic yarn at a high speed.
The present invention specifically relates to a bobbin holder which can smoothly and surely hold a bobbin.
Further, the present invention relates to a bobbin holder installed in a yarn winding apparatus which can simultaneously wind a plurality of yarns.
In conventional bobbin holders, as described in Japanese Utility Model Application Laid-open No. Sho 60-1766 and U.S. Pat. No. 4,458,850, a ring-like elastomeric member inserted onto a rotatable cylindrical support is compressed in an axial direction so that a bobbin is held.
In such a bobbin holder, a large force is necessary because the ring-like elastomeric member is compressed in an axial direction and is deformed.
The elastomeric member is compressed by a spring disposed at a front end of the rotatable cylindrical support. Because of frictional resistance between the elastomeric member and the support or bobbins, the force for compressing the elastomeric member at the rear side of the support is smaller that for compressing the elastomeric member at the front side of the support, and accordingly, the elastomeric member located at the rear side is hard to be deformed. Therefore, there occurs a problem that the insides of bobbins are not held completely, and that accordingly, the bobbins are loosened during winding operation and vibrate.
Further, in a conventional bobbin holder for holding a plurality of bobbins described in the above-mentioned U.S. Pat. No. 4,458,850, compressed air in a cylinder chamber is exhausted when the bobbins are held. As a result, the bobbin holding devices and the elastomeric members, which are alternately inserted on the rotatable support member, are compressed by compression means, such as a coned disc spring. Thus, the bobbin holding device disposed at the rear end of the rotatable support member is compressed via the bobbin holding device disposed at the front end and the cylindrical member.
Accordingly, the bobbin holding device disposed at the front end is subjected to sliding resistance between the rotatable support member and the cylindrical member, sliding resistance between the bobbin holding device and the rotatable support member, and sliding resistance between the bobbin holding device and the inner surface of the bobbin, as well as the force for deforming the rubber ring located near the rear end when the bobbin holding device is made of a rubber ring. As a result, the force acting on the bobbin holding device located near front end is larger than the force acting on the bobbin holding device located near rear end.
Therefore, the bobbin holding device located near front end holds the bobbin earlier than the bobbin holding device located near rear end does. Consequently, the force transmitted to the bobbin holding device located near the rear end becomes small. Accordingly, the bobbin holding device located near the rear end is not completely in contact with the inner surface of the bobbin nor the outer surface of the rotatable support member, and the force for holding the bobbins become insufficient.
As a result of the insufficient bobbin holding force, the bobbins may vibrate, and accordingly, the winding apparatus may generate noise and is dangerous in some cases. In addition, bearings supporting the rotatable support member may be damaged because of the vibration. Furthermore, the yarns which are wound on the bobbin may be rubbed between the bobbin surfaces and a contact roller because of the vibration of the bobbins, and accordingly, the yarn quality is reduced.
Besides, during the yarn winding operation, the chucking portion of the bobbin holder may be deviated because of the weight of the wound packages, and the above-described vibration is enhanced, and accordingly, the wound package may be deformed.
In the meantime, the amount of yarn wound on a bobbin is recently increasing, and the number of bobbins held on a single bobbin holder is also increasing, and correspondingly, the numbers of the bobbin holding devices and the cylindrical members increase. Accordingly, the above-described insufficient bobbin holding force and deformation of the wound package become remarkable.
As described in other prior art, such as Japanese Utility Model application Laid-open No. Sho 57-96144 or Japanese Utility Model application Laid-open No. Sho 50-142836, there, has been known a bobbin holder which comprises a pair of frustoconical members each having an inclined portion and a cylindrical member having an inclined inner surface, and the the pair of frustoconical members axially press the cylindrical member so that the outer surface of the cylindrical member is kept in close contact with the inner surface of the bobbin.
In these bobbin holders, the outer surface of the cylindrical member is always in close contact with the inner surface of the bobbin when a yarn is wound on the bobbin. However, the cylindrical member is formed in one body and therefore is rigid. Accordingly, the diameter of the cylindrical member will not be easily changed, and accordingly, the inner surface of the cylindrical member is spaced from the rotatable support member. During the winding operation, small vibration may be caused because of ribboning of the wound yarn or unbalance of the wound yarn package.
Further, the weight of the package and the contacting forces are applied to the bobbin holder under the small vibration, the portion where the rotatable support member and the cylindrical member engage with each other is beaten. Accordingly, clogging between the rotatable support member and the cylindrical member may occur. Consequently, the cylindrical member does not work well, and therefore, there occur problems that bobbins cannot be held well or that the held bobbins cannot be released.